Mast step/tube repair

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New Member

The mast tube on my sunfish is leaking. i pored resin and fiberglass scraps in the bottom just slightly over the ridge previously. it looks like there is some loose pieces of fiberglass on the inside of the boat.
Should I wrap the outside of the tube and reinforce the lower half of the tube to the boat?
Is this (pic of the red boat) the proper place to cut a port?

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Active Member

Failure usually happens when the mast tube breaks loose from the bottom of the boat.
Seems like they always did a quick and ugly job. You'll have to do a lot of grinding with
a dremel tool to get the area cleaned up before you can lay down new fiberglass. Careful
not to detach the mast tube as it's not easy to get the mast perfectly vertical once
the tube is loose. If you think it's attached solidly and you're not into sailing in
high winds you could just leave as is and wrap the mast tube in a couple layers
of fiberglass. The down side is once the mast breaks loose sailing it cracks the
deck and makes a big mess. Short of popping the deck that's where you'd put
the inspection port. I'd make sure to put a reinforcement ring under it as the
port will be taking some stress from the deck. The stress aspect almost makes
me think popping the deck would be better. Usually when you see a repair where
the mast has broken loose they end up re fiber glassing the entire area around
the mast hole. More that one way to skin a cat so do the repair according to
you comfort level. Oh, a leak could indicate mast has started to pull away from
the hull or the job was flawed from the factory. Viva La Sunfish, a model of
fine craftsmanship it never was.

New Member

I have separated the bow just enough for the backerblock but I really don't want to do that again.
I could not find reinforcement rings listed. Do you make them? Maybe out of a plastic kitchen cutting board?
For the strips of glass attaching the tube to the hull, do I grind off half of them and put new ones down that way it's still keeps position but might bond better? Or scuff and glass over everything?

Well-Known Member

Active Member

The reinforcement ring could be made out of plywood, split at a angle and
corkscrewed into the inspection port hole. Trying to work through a hole
is difficult. I'm wondering if it would be easier to use 2-part epoxy putty
around the base of the mast tube. If you scuff and glass you are assuming
what was laid down at the factory is still secure. Seeing as there is no was
to test it I guess it just comes down to whether it's worth the trouble or not.

Well-Known Member

Now that you've separated the deck, what is the dark material that surrounds the mast tube at the arrow?

I only ask, as it's easier to work on the deck and hull, should the mast tube be totally removed from the boat. (For inspection and repair).

Alternately, the tube can be cut off, the hull cut out, repair to base more readily made, and reinstalled with a fiberglass sleeve (external to the existing mast tube at the deck). The weight penalty would be minimal, the hull would be more resistant to flexing, and the mast tube twice as strong as factory.

Well-Known Member

Now that you've separated the deck, what is the dark material that surrounds the mast tube at the arrow?View attachment 26462

I only ask, as it's easier to work on the deck and hull, should the mast tube be totally removed from the boat. (For inspection and repair).

Alternately, the tube can be cut off, the hull cut out, repair to base more readily made, and reinstalled with a fiberglass sleeve (external to the existing mast tube at the deck). The weight penalty would be minimal, the hull would be more resistant to flexing, and the mast tube twice as strong as factory.

Well-Known Member

There's more than one way to do this repair. We've seen an experienced Sunfish restorer (Mixmkr) here fix everything from through the hull (underneath). Overall, his are invisible—yet lightweight—and strengthening repairs.

Mast steps haven't been a problem with my five Sunfish (formerly six), but if I wanted to keep the original straight-up mast position, this is how I'd tackle it. Especially as working through a small port makes too much of the endeavor guesswork, which may require a later "redo".

The "Ultimate Inspection Port" allows the passage of large corded tools, but I'd still prefer taking-on this repair once I've eyeballed the problem outside the Sunfish.

New Member

I'm not sure what the dark ring is. I didn't install it and the boat wasn't opened up before me. Maybe reinforcement ring?
I'm thinking I'll either use a borescope or video chat myself inside the boat. I will also be able to fit a die grinder my existing 5" port behind the coaming so that will give me more room.

Member

Did you retest for leaks after you applied the resin? Are you sure the mast tube is loose? As others have said sunfish do not usually have issues with the mast tube. I would have leaked tested and gone sailing unless you put a big load on the mast. I would put a mast cleat on for the halyard to lower the load on the hull and deck.

New Member

The mast tube is not loose. Only leaks but it doesn't look very nice from inside the boat.
I filled bottom of the mast with resin/fiberglass bits and it held water over night. I used the boat 5 times and now the mast tube leaks again.

Active Member

Well, it's always good to know about impending failure even if you don't know what's
failing. Perhaps you can make a cap for the mast hole, pour in some soapy water and
pressurize the mast hole. If there is water in the mast tube I would assume water might
be coming in from a leak in the hull somewhere. These older boats tend to leak at the
hull/deck seams. Mostly where the hull flexes across from the ends of the splash guard.

New Member

I have leak tested the boat. The it has a couple screw hole leaks but the mast hole is the only major leak. It also no longer holds water in the tube. I could pore another 1/2 of resin/glass shreds and fix the leak but I'm not sure how far above factory I should fill the tube.

I'm also concerned about the the glass cloth that is sticking out (arrows in pic)

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Well-Known Member

I have leak tested the boat. The it has a couple screw hole leaks but the mast hole is the only major leak. It also no longer holds water in the tube. I could pore another 1/2 of resin/glass shreds and fix the leak but I'm not sure how far above factory I should fill the tube. I'm also concerned about the the glass cloth that is sticking out (arrows in pic)

I wouldn't exceed the factory depth at all. The leverage of a mast with a filled sail could damage the mast tube. If more than an 1\8 inch has been added with your mix, I'd sand down to near-normal depth.

Try another mix, but wrap the mast with something like a thin layer of Styrofoam coffee cup and masking tape. (Something that rapidly deteriorates). Displace your mix to fill the tube better and higher, (with the wrapped mast or a substitute) but assure the mast can be removed afterwards!

Breeze Bender

I would try to pinpoint the leak a bit more. If you fill the mast tube half way does it drain right into the hull? Or does it hold water? Maybe it only leaks when you fill it all the way? Since you've already got good access to the interior I'd AVOID adding any more resin/mix to the mast hole unless you can see chips/cracks in the wall of the tube. Use fiberglass tape (it's not tape, but it comes in strips that have finished ends so it's easier to work with) and wrap the tube from inside the hull. Cover your deck so you don't drip resin on it. Just painting thickened epoxy around the mast step from inside the hull is probably enough, may not need the tape, but I guess it would be added insurance.

New Member

I got the fiberglass tape, got a port and cut the hole. It has more gaps that i was expecting between the tube and the mast step. Should I remove material where the bottom portion fares out or just add thickened resin there?
Should I put thickened resin on hull where it connects then put glass over that?

Planing into eternity...

On "The Good, The Bad & The Ugly" scale, well, Tuco would be proud of this one... just glancing at that step tube and the strips radiating outward from it, one can see that the glass was never wetted thoroughly. I'd take a file to some of that trash on the step tube, maybe a razor knife if it's still soft, then do the job again, wetting the tube first, wrapping the glass strips around it more tightly, and adding resin to ensure that the whole shebang is thoroughly wetted. Do the last by holding the glass in place with one hand and brushing more resin all around it so all glass fibers are saturated. Don't worry about a little resin running down toward the radiating strips, you're gonna need to hit those again anyway with a good layer of resin, AFTER slicing open or otherwise holing the air pockets under those strips as you prep. When I do step tube work, I have the pot of catalyzed resin nearby inside the hull so I'm not slopping it everywhere... latex gloves work well for smoothing out the glass on the vertical tube. Spread whatever resin is left over the radiating strips below, being sure to fill all air pockets and saturate all dry cloth.

Once these first tasks are complete and the resin is cured, you might wanna cover all those radiating strips at the base with one big glass "donut": cut the piece so it covers all the strips radiating outward, then wet the existing surface, lay the piece in place, and wet it again to solidly "cement" all those strips under one "blanket" (so to speak, think of the cloth cover your folks used to place around the base of the Christmas tree, only this "blanket" should be snug with no air bubbles or dry cloth in sight). Depending on how your initial task of improving that step tube goes, you might wanna add more strips running vertically or diagonally downward and outward like the strips seen at the base of the tube. Either way, those strips radiating outward at the base should all be covered with at least one piece of cloth cut to shape, that last piece will help hold everything together a bit longer, aye? Same goes for any strips on the step tube, they should be covered with at least one good wrap.

I see from your photos that some of the glass cloth was never sufficiently wetted and worked into place around the compound curve at the base of the step tube. Compound curves are tricky, you want to be sure the weight of cloth you're using is right for the job, meaning pliable when wet, otherwise it'll be difficult to make the glass conform and adhere to the prepped surfaces & curves. I always liked to initially place a bit of glass rope round the very base of the step tube, it made for a more solid repair with no air pockets or "Rice Chex" like the ones seen in your pics. Don't be shy with the resin when you first wet the area, in this particular case it's okay for surplus resin to run down and cover those strips below. Get the step tube wrapped well with the cloth, then finish wetting it and saturating it, carefully smoothing out air bubbles with brush or glove in the process. Air bubbles & dry "Rice Chex" cloth mean weakness, which you don't want, you want the strongest possible bond, yeah?

Not trying to put down your work, just giving you the straight facts... the good news is that even the worst botched glass jobs can be put right again, it just takes a little more time and costs a little more money for materials, LOL. Remember that line from "FULL METAL JACKET" by director Stanley Kubrick? After the sniper gets whacked, that one hand tells Joker he should receive "The Congressional Medal of Ugly!!!" Well, this mast step in its current condition should receive that Hollywood medal, LOL. But I have faith in ya, I know you can make things right... starting with a file or a razor knife. Won't be long before you have a nice solid mast step repair, no air bubbles or dry "Rice Chex" cloth in sight. So no worries, you'll soon be sailing that bad girl like a crusty nautical demon, LOL. Good luck to you, just stay focused on each task one step at a time, and you'll git 'er done... time for another cold beer, CHEERS!!!

Active Member

1. Nothing the customer will ever see.
2. It's not like this has to stay intact for 50 years.
3. If we did a better job, we would have to charge you more.
4. Quitting time's in one hour, let's get this thing done.

I'm not sure how relevant number four is since all the
Sunfish I've seen look this bad, some worse.